Since solar batteries do not have a power storage function, various power generation systems incorporating a solar battery and a storage battery together have been conventionally proposed.
For example, patent document 1 discloses an alternating-current end commercial switching (without a system linkage) solar battery power supply system in which a storage battery is connected through a charge and discharge control circuit to a connection point between a solar battery and an invertor.
For example, patent document 2 discloses a solar power generation system in which a storage battery is connected through a charge and discharge controller to a connection point between a solar battery and a system linkage invertor having a self-operation function. In the solar power generation system disclosed in patent document 2, auxiliary charge for the storage battery is performed using power on the side of the commercial power system.
For example, patent document 3 discloses a solar power generation system in which power generated by a solar battery device is fed through a current control portion or a charge and discharge control portion to a storage battery portion or an invertor device, and which switches the following three methods: a control circuit controls the current control portion or the charge and discharge control portion and the storage battery portion, and thus the power generated by the solar battery device is used only for charging the storage battery portion; the power generated by the solar battery device is used only for being fed to the invertor device; and both the power generated by the solar battery device and the power of the storage battery are fed to the invertor device. Furthermore, in the solar power generation system disclosed in patent document 3, the storage battery is charged by the power from the solar battery or the power from the power system.